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Sorption and desorption in raw and parboiled paddy
Author(s) -
Craufurd R. Q.
Publication year - 1963
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740141011
Subject(s) - husk , cracking , sorption , moisture , water content , starch , desorption , chemistry , raw material , absorption of water , agronomy , pulp and paper industry , food science , materials science , botany , composite material , adsorption , organic chemistry , geotechnical engineering , engineering , biology
Abstract Experiments on the drying and remoistening of raw and parboiled paddy are described. The different effects of remoistening with water or water vapour are discussed and also the effects of fast and slow drying. The absorption of liquid water causes cracking of the grain up to 15% moisture content. Above 15% there is no further cracking. On absorption, the drier the paddy the greater is the degree of cracking. Slow drying does not cause cracking but fast drying does so when the moisture content is below 15%. With fast drying, cracking is not only caused when passing the 15% point but also when drying, e.g., from 13.0 to 12.0% moisture content. The importance of temperature in causing cracking is discussed. Parboiled paddy dries faster than raw paddy, because the husk is more loosely attached in the former; raw dehusked paddy and parboiled dehusked paddy dry at approximately the same rate. These results are discussed in relation to work on other starchy seeds and particularly to Fish's recent work on sorption and desorption in potato starch. It is suggested that the changes observed in paddy can be related to the peculiar properties of starch which obtain below 15% moisture content.